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The Florida Institute of Phosphate Research was created in 1978 by the Florida Legislature (Chapter

378.101, Florida Statutes) and empowered to conduct research supportive to the responsible

development of the state's phosphate resources. The Institute has targeted areas of research

responsibility. These are: reclamation alternatives in mining and processing, including wetlandsreclamation, phosphogypsum storage areas and phosphatic clay containment areas; methods for

more efficient, economical and environmentally balanced phosphate recovery and processing;

disposal and utilization of phosphatic clay; and environmental effects involving the health and

welfare of the people, including those effects related to radiation and water consumption.

FIPR is located in Polk County, in the heart of the central Florida phosphate district. The Institute

seeks to serve as an information center on phosphate-related topics and welcomes information

requests made in person, or by mail, email, or telephone.

Executive Director

Paul R. Clifford

Research Directors

G. Michael Lloyd, Jr. -Chemical Processing

J. Patrick Zhang -Mining & Beneficiation

Steven G. Richardson -ReclamationBrian K. Birky -Public & Environmental

Health

Publications Editor

Karen J. Stewart

Florida Institute of Phosphate Research

1855 West Main StreetBartow, Florida 33830

(863) 534-7160Fax: (863) 534-7165

http://www.fipr.state.fl.us

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PILOT PROJECT TO TEST NATURAL WATER TREATMENT CAPACITY OFWETLAND AND TAILING SAND FILTRATION ON MINED PHOSPHATE LANDS

FINAL REPORT

Peter J. Schreuder, CPGPrincipal Investigator

SCHREUDER, INC.110 West Country Club DriveTampa, Florida 33612 USA

Prepared for

FLORIDA INSTITUTE OF PHOSPHATE RESEARCH1855 West Main Street

Bartow, Florida 33830 USA

Project Manager: Steven G. RichardsonFIPR Contract Number: 98-03-136

and

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT2379 Broad Street

Brooksville, Florida 34609 USA

Contract Manager: Mark D. Barcelo, P.E.Manager of the Hydrologic Section

SWFWMD Agreement Number: 99C0NN0008

March 2005

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DISCLAIMER

The contents of this report are reproduced herein as received from the contractor. Thereport may have been edited as to format in conformance with the FIPRStyle Manual.

The opinions, findings and conclusions expressed herein are not necessarily those of theFlorida Institute of Phosphate Research, nor does mention of company names or productsconstitute endorsement by the Florida Institute of Phosphate Research.

2005, Florida Institute of Phosphate Research.

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PERSPECTIVE

Demand for water in central Florida is increasing while the availability ofgroundwater is dwindling. Lowered aquifer levels from municipal and industrial pumping

have increased the threat of saltwater intrusion in coastal areas and have affected springflows in more inland areas. The Southwest Florida Water Management District(SWFWMD) is proposing to cut back on the permitted quantities of water pumped from theFloridan Aquifer in the Southern Water Use Caution Area (SWUCA) so as to be closer tosustainable yield levels. This will have a significant impact on current, and especiallyfuture, water users. To meet the growing demands of development, alternative sources ofwater must be sought. Possible sources are reclaimed wastewater, the capture of stormwater, the capture of "excess" surface water, development of the surficial aquifer, anddesalinization of seawater.

The idea of storing water in reservoirs created from mine pits has been around for

some time; however, that water is subject to evaporative losses, must be piped to theusers, and must be treated before use. Getting the water into the ground as rapidly aspossible would reduce evaporative losses, would help restore a depleted aquifer, and theaquifer itself could be used as the pipeline if the production well was some distancefrom the injection well. To avoid degradation of the aquifer, the injected water must be ofequal or better quality than the water already in the aquifer. This project is part of aneffort to examine the feasibility of temporarily storing wastewater or excess surface waterin small surge reservoirs on mined lands, purifying the water with wetland treatment andsand tailings filtration, and then injecting the treated water into the Floridan Aquifer. Theproject reported here was a field test of a treatment wetland and a sand tailings filtrationbasin conducted on former phosphate mined lands at the Progress Energy Florida, HinesEnergy Complex in Polk County, Florida. FIPR and SWFWMD (including its associatedBasin Boards) equally shared the cost of this study, while Progress Energy Floridaprovided the site and some in-kind services.

The goals of the project were to:

Demonstrate in a pilot-scale project on mined lands the effectiveness of wetlandtreatment followed by tailing sand filtration for purifying surface waters to meetdrinking water quality standards.

Collect water quality and design data that could be used in developing full-scaleprojects.

A 1.5-acre tailing sand filtration bed was constructed and an existing wetland in aU-shaped ditch, 8400 feet in length, was used. Waters from two sources were tested inthe system: water from the power plant cooling pond (August 2002 to March 2003) andwaste water from the city of Bartow (April 2003 to December 2003).

The main purpose of the sand filter was to remove particulates andmicroorganisms, and the sand filter did indeed drastically reduce bacterial counts, although

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water coming through the sand filter in the field test sometimes exceeded drinking waterstandards for coliform bacteria. In an earlier laboratory study (FIPR Publication No. 03-124-153), microorganism removal was very effective when a sufficient unsaturated zone wasmaintained at the surface of the sand columns. It is thought that situations that causedgreater saturation of sand at or near the surface of the sand filter may be related to the

occasional exceedance of the drinking water standard for coliform bacteria in the fielddemonstration. Better water level control (i.e., better control of the inflow and outflowpumps) may solve this problem. Additionally, a steadier flow of water (in contrast withfrequent pump shutdowns due to lightning, etc.) will likely promote the development of abiologically active surface film (or schmutzdecke) that should aid bacterial removal. Theauthors also suggest that a UV system could be added to kill bacteria that may occasionallyget through the sand filter.

For many parameters, the cooling pond water was of fairly good quality to beginwith. The sand filter reduced coliform bacterial counts, but iron and manganeseconcentrations actually increased after the water passed through the wetland and sand filter,

probably due mainly to dissolution of iron and manganese mineral impurities in the sand.The lowering of TDS, sodium and chloride by the system was attributed to dilution byrainfall, but sulfate concentrations were lowered to a greater extent than could be accountedfor by dilution, suggesting biological reduction of the sulfate in the wetland. Wetlandstypically have low redox potentials, and the chemically reduced water from a treatmentwetland may lower the risk of pyrite oxidation and the resulting arsenic release that has beenobserved in some cases when highly oxygenated water (high redox potential) has beeninjected into the Floridan aquifer.

The effluent had higher concentrations of nitrate and total phosphorus than thecooling pond water, and wetland treatment was effective in lowering these concentrations.Fluoride was increased by passing the effluent water through the wetland and sand filter, butit was below the drinking water standard. Iron increased slightly after the effluent waterpassed through the wetland and sand filter, but manganese did not. Lower levels of Fe andMn when effluent water passed through the sand filter than when cooling pond waterpassed through the sand filter may have been due to those metals being leached to lowerlevels in the sand by the time the effluent water was applied (waste water was tested afterthe cooling pond water test). Other tests have shown that cleaner sands (lower levels ofclay or apatite minerals) have much lower levels of iron or manganese in the leachate.

Other FIPR-funded projects on this topic include:

Potential Use of Phosphate Mining Tailing Sand for Water Filtration: LeachingTests (FIPR Publication No. 03-113-154). This report addressed the leaching ofsand tailings in barrels as a first step in determining the effects of sand tailingfiltration on water quality.

An Investigation of the Capacity of Tailing Sand to Remove Microorganismsfrom Surficial Waters (FIPR Publication No. 03-124-153). This was alaboratory column leaching study to examine microorganism removal by sand

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tailing filtration. Sufficient depth of the surface unsaturated zone and lowerrelative permeability of the sand were important factors in the effective removalof microorganisms.

Feasibility of Natural Treatment and Aquifer Recharge of Wastewater and

Surface Waters Using Mined Phosphate Lands: A Concept to Expand RegionalWater Resource Availability (FIPR Publication No. 03-113-186). This projectexamined the feasibility, including costs, of several potential real worldpossibilities for water treatment and storage on mined lands.

Water Quality Investigation of In-Situ Tailing Sand Deposits Under NaturalEnvironmental Conditions (FIPR Publication No. 03-129-185). Examinedwater quality in several sand tailings deposits in the field. Iron was greaterthan the 0.3 mg/l standard in nine of the 12 sites, but three were below.Manganese was higher than the 0.05 mg/l standard at seven of the twelvesites, but five were below. In all cases, fluoride was below the 4.0 mg/l

standard, and sulfate was below the 250 mg/l standard.

Steven G. RichardsonFIPR Reclamation Research Director

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ABSTRACT

This project involves the treatment of flood surface waters by and reclaimed watertreatment through natural processes on lands previously mined by phosphate mining

companies. As a result of the mining process, the phosphate companies produce openmine pits, clay settling areas (CSA) and tailing sand deposits, which the companies arerequired to reclaim as land and lakes, wetlands, pastures, and agricultural lands.

The basis for this project was the premise that the natural systems, in particular,wetlands created on CSAs followed by tailing sand filtration, will remove the organic,inorganic and microbiological contaminants from the waters, resulting in water that willmeet drinking water standards. After collecting and analyzing a total of 725 watersamples from the end point of the natural treatment system at the tailing sand filter basin,all EPA and State of Florida mandated Primary and Secondary Drinking Water Standards(PDWS/SDWS) were met except for a few parameters. The parameters that exceeded

SDWS were iron, manganese, fluoride, color, and odor, which are parameters thatcommonly occur in natural groundwater at concentrations exceeding the secondarydrinking water standards. There were two exceedances of chloroform, which is found inthe Group 2 Unregulated drinking water standards, but all other parameters found inPDWS, Volatile Organic Compounds, Synthetic Organic Contaminants (pesticides andherbicides), Group 1 Unregulated, Group 3 Unregulated, and Radionuclide parameterswere either undetected in the laboratory analyses or were detected, but at concentrationslower than the drinking water standard for that parameter. During the study,Cryptosporidium and Giardia were never found present in the filter basin, but bothmicroorganisms were found present in the wetland and in the water from the coolingpond and effluent discharge. In varying concentrations, fecal and total coliform werefound present in the wetland, cooling pond, and effluent discharge on a regular basis;however, total coliform concentrations exceeded the recommended limit of 4 colonies perunit of 100 milliliters less than 30 percent of the time in the water pumped from the filterbasin. SI attributes the presence of total coliform to high water levels within the filterbasin because of several, re-occurring operational impacts and very rainy periods. Thereis also a hypothesis that the very low nutrient and very low total dissolved solidsconcentration in the water pumped from the treatment wetland in combination with thevery high vertical hydraulic conductivity of the filter bed tailing sands prevented theformation of a biologically active layer at the sand/water interface commonly referred toas the schmutzdecke. The function of the schmutzdecke is (among others) to removecoliform bacteria. In addition to these constraints, the periodic nature of the wetlandpumpage did not help to promote the development of this biofilm.

An additional important finding is a reduction in surface water temperatureaveraging 5.4 C with a maximum of 8.5 C while flowing through the wetland.Additionally, during filtration through the tailing sand filter the temperature increased byan average of 1.3C. The average net difference in temperature of the water flowing intothe wetland and the treated and filtered water flowing from the filter basin is 3.9 C, witha maximum of 9.8

C.

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ACKNOWLEDGEMENTS

The principal investigator wishes to acknowledge the valuable support he hasreceived during the conduct of this project from the FIPR Research Director Dr. Steven

Richardson, from the SWFWMD representative Mark Barcelo, P.E. and from therepresentatives of Progress Energy Florida (PEF), Mr. Kent Hedrick, P.E. and RandyMelton, CEP. He also gratefully acknowledges the in-kind contribution from PEF, whichprovided the site, constructed the electric power supply lines and provided the electricalservice free of charge. The constant watch of PEFs security detail was an importantfactor in the safety and constancy of the operation. The success of such a project isdirectly related to the attention to detail for the field operations as well as the data andsample collection that was given by the hydrologic field technician Dana Gaydos. Shealso assisted in the recording and management of the large database and along with JulieK. Earls, in the preparation of this report. John M. Dumeyer, P.E., P.G., Holly L. Regar,and Nicholas C. Schrier provided additional contributions to the successful

implementation of the project.

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TABLE OF CONTENTS

PERSPECTIVE.................................................................................................................. iii

ABSTRACT...................................................................................................................... vii

ACKNOWLEDGEMENTS............................................................................................. viii

EXECUTIVE SUMMARY .................................................................................................1INTRODUCTION ...............................................................................................................5

Purpose and Objectives of Current Investigation ....................................................5Location of Project Area..........................................................................................6Selection of Location of the Project Area................................................................9

Project History .......................................................................................................13

DESIGN AND CONSTRUCTION OF TREATMENT SYSTEM...................................17

Project Configuration.............................................................................................17Design of Individual Project Elements ..................................................................17Construction of Individual Project Elements.........................................................19

RESULTS AND DISCUSSION........................................................................................21

Overview................................................................................................................21Results....................................................................................................................22Discussion..............................................................................................................31

Performance Assessment ...........................................................................31Physical Parameters ...................................................................................32Volume Pumped.........................................................................................32Rainfall and pH..........................................................................................33Specific Electrical Conductance ................................................................37Temperature ...............................................................................................37Turbidity ....................................................................................................40Color ..........................................................................................................41Odor ...........................................................................................................41Total Dissolved Solids ...............................................................................42Inorganic Chemicals ..................................................................................42Iron and Manganese...................................................................................43Fluoride......................................................................................................44Sodium, Chloride and Sulfate....................................................................45Nutrients.....................................................................................................47Organic Chemical Compounds..................................................................48

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TABLE OF CONTENTS (CONT.)

Volatile Organic Compounds ....................................................................48Trihalomethanes.........................................................................................48

Microorganisms .........................................................................................49Treatment Assessment ...............................................................................55Treatment Capacity....................................................................................57Wetland Detention .....................................................................................58Wetland Performance.................................................................................58Filter Basin Treatment ...............................................................................60Entire System Treatment............................................................................61System Performance for Recharge.............................................................62

CONCLUSIONS AND RECOMMENDATIONS ............................................................65

Conclusions............................................................................................................65Recommendations..................................................................................................65

Project Specific ..........................................................................................65General.......................................................................................................66

REFERENCES ..................................................................................................................67

APPENDIX A. DETAILED DESCRIPTION OF PROJECT TIMELINE EVENTS... A-1APPENDIX B. PROJECT DESIGN INFORMATION..................................................B-1

Testing of Filter Basin Materials .........................................................................B-1Design of the Tailing Sand Filter Basin...............................................................B-1Design of the Linear Wetland System .................................................................B-2Design of the Pumping Stations...........................................................................B-2

Cooling Pond ...........................................................................................B-2Effluent Line ............................................................................................B-3Plant Island...............................................................................................B-3SA-8 .........................................................................................................B-3

APPENDIX C. PROJECT CONSTRUCTION INFORMATION .................................C-1

Construction of Project Elements ........................................................................C-1

Sand Tailing Filter Basin and Pumping Station.......................................C-1Linear Wetland System and Pumping Station .........................................C-4Cooling Pond Pumping Station................................................................C-7Effluent Pumping Station.........................................................................C-7

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TABLE OF CONTENTS (CONT.)

SA-8 Pumping Station .............................................................................C-9Plant Island Stormwater Drainage Ditch Pumping Station....................C-10

APPENDIX D. OPERATIONAL CONSTRAINTS ..................................................... D-1

Equipment ........................................................................................................... D-1Climatic............................................................................................................... D-3Operational.......................................................................................................... D-5

APPENDIX E. RESULTS OF ANALYSES PER GROUPING AND SOURCE .........E-1

Performance Standards ........................................................................................E-1

Cooling Pond ...........................................................................................E-1Effluent ....................................................................................................E-1

APPENDIX F. PRIMARY/SECONDARY STANDARDS........................................... F-1

Cooling Pond ....................................................................................................... F-1Effluent ................................................................................................................F-1

APPENDIX G. FULL SUITE........................................................................................ G-1

Cooling Pond ...................................................................................................... G-1Effluent ............................................................................................................... G-1

APPENDIX H. MICROORGANISMS ......................................................................... H-1

Cooling Pond ...................................................................................................... H-1Effluent ............................................................................................................... H-1

APPENDIX I. PHYSICAL PARAMETERS .................................................................. I-1

APPENDIX J. SCHREUDER, INC. BARREL TEST ....................................................J-1

Background...........................................................................................................J-1Project Design.......................................................................................................J-1Sampling Period and Set-Up.................................................................................J-2Flow Calculations Methodology...........................................................................J-2Water Quality Sampling Methodology.................................................................J-3Operational Description of Components in Barrel Test .......................................J-3Sampling Procedure..............................................................................................J-7

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TABLE OF CONTENTS (CONT.)

Microorganisms ........................................................................................J-7TP, NO3

-, NO2, SO4

=, TSS, TOC, NH3 and Color....................................J-8

Field Parameters....................................................................................................J-8Results ...................................................................................................................J-8

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LIST OF FIGURES (CONT.)

Figure Page

C-1. Tailing Sand Filter Basin Pumping Station ...................................................C-2C-2. Filter Basin Looking East Showing Electric Equipment ...............................C-3C-3. Wetland System Pumping Station .................................................................C-6C-4. Cooling Pond Design .....................................................................................C-7C-5. Effluent Design ..............................................................................................C-8C-6. SA-8 Pumping Station ...................................................................................C-9C-7. Plant Island Stormwater Drainage Ditch Pumping Station..........................C-10J-1. Top View of Barrel Test Set-Up.....................................................................J-5J-2. Side View of Barrel Test Set-Up ....................................................................J-6J-3. Close-Up View of Barrel Test Set-Up............................................................J-7J-4. Results of Color Sampling Events ..................................................................J-9

J-5. Barrel Test Calculated Hydraulic Conductivity............................................J-11J-6. Barrel Test Total Coliform Results...............................................................J-12J-7. Removal Efficiency of Inflow with All Barrels............................................J-13J-8. Removal Efficiency of Barrel A with Hydraulic Conductivity ....................J-14J-9. Removal Efficiency of Barrel B with Hydraulic Conductivity ....................J-15J-10. Removal Efficiency of Barrel C with Hydraulic Conductivity ....................J-16J-11. Barrel Test Fecal Coliform Results...............................................................J-17J-12. Front View of Barrels ...................................................................................J-18J-13. Far Side View of Barrels Showing Reservoir and Electric Set-Up ..............J-18J-14. Side View of Barrels.....................................................................................J-19

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LIST OF TABLES

Table Page

1. Timeline of 2000 through 2004 .......................................................................152. Number of Samples Collected .........................................................................233. Samples and Exceedances for Primary Drinking Water Standards .................254. Samples and Exceedances for Secondary Drinking Water Standards .............265. Samples and Exceedances for Volatile Organic Compounds..........................276. Samples and Exceedances for Synthetic Organic Compounds........................287. Samples and Exceedances for Group I Unregulated Compounds ...................298. Samples and Exceedances for Group II Unregulated Compounds..................309. Samples and Exceedances for Group III Unregulated Compounds.................3010. Samples and Exceedances for Microorganisms...............................................3111. Samples and Exceedances for Radionuclide Contaminants ............................31

12. Reductions in Median Concentrations of Sodium, Chloride andSulfate in the Treatment System.................................................................4613. Comparison of Frequency Distribution of Total and Fecal Coliform

Concentrations in Wetland and Basin for Both Water Sources..................5214. Median Values of Chemical Compounds That Never Exceeded

PDWS/SDWS with Cooling Pond Water as the Source.............................5515. Median Values of Chemical Compounds and Physical Parameters

That Exceeded PDWS/SDWS with Cooling Pond Water as the Source....5616. Median Values of Chemical Compounds That Never Exceeded

PDWS/SDWS with Effluent as the Source.................................................5617. Median Values of Chemical Compounds and Physical Parameters

That Exceeded PDWS/SDWS with Effluent as the Source........................5718. Exploratory Well TW-1 Versus Treatment System Results ............................63

APPENDIX TABLES

A-1. Timeline of 2000........................................................................................... A-1A-2. Timeline of 2001................................................................................... A-2, A-3A-3. Timeline of 2002........................................................................................... A-4A-4. Timeline of 2003.................................................................................... A-5,A-6E-1. Results of the Performance Standards from the Cooling Pond...........E-1 to E-7E-2. Results of the Performance Standards from the Effluent..................E-8 to E-13F-1. Results of the Primary and Secondary Drinking Water Standards

from the Cooling Pond........................................................................ F-2 to F-6F-2. Results of the Primary and Secondary Drinking Water Standards

from the Effluent............................................................................... F-7 to F-12G-1. Results of the Full Suite from the Cooling Pond ............................... G-2 to G-8G-2. Results of the Full Suite from the Effluent ...................................... G-9 to G-26H-1. Results of Microorganisms from the Cooling Pond ..................................... H-2

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The above-mentioned publication number 03-113-186 contains a paragraphPermitting Requirements for Implementation (of ARRP) on page 14 providing asynopsis of the regulatory requirements to obtain a permit to construct and operate anARRP system. The Florida Department of Environmental Protection (FDEP) will beresponsible for the reservoirs, dams, clay settling areas, wetlands and the recharge

well(s). Diversion of surface water and the recovery of recharged water is primarily theresponsibility of the Southwest Florida Water Management District (SWFWMD), alongwith wetland issues. The US Army Corps of Engineers (USACOE) will also be involvedin reservoirs as well as wetland issues.

While this report documents the feasibility of implementing the ARRP conceptbased on the availability of water and reasonable unit cost, the question of theacceptability of the quality of the water leaving the natural treatment system remained.To address this question a pilot study was proposed, accepted by the FIPR, constructedand operated for three years. This document reports the construction of the pilot projectusing a wetland system and tailing sand filter basin, as well as the results of the chemical

analyses of water samples and field data collected during the two years of actualoperation. While the original plan called for a three-year project, operational problemsextended the project by 1.5 years. Notwithstanding, the results of the project are quitepromising. Of all the primary and secondary drinking water standards (PDWS/SDWS),including those for Unregulated Group I, II, and III contaminants, radionuclides, andmicroorganisms, the project documented only five parameters (in the SDWS list) thatexceeded the recommended levels from time to time. The only other occasionalexceedance was for total coliform with concentrations of 4.0 MPN/100 ml or greater.During the last year of operation, this concentration limit was exceeded less than thirtypercent of the time. Schreuder, Inc. has identified the most probablemechanical/operational cause.

The other parameters that exceeded the SDWS standards were iron, manganese,fluoride (initially), color and odor. Schreuder, Inc asserts that with a careful selection ofthe tailing sand that is used in the construction of the filter basin, the iron, manganese andfluoride exceedances will be significantly reduced or eliminated. A better distribution ofthe water to be discharged to the surface of the filter basin and a more constant dischargeof that water in combination with filter sand surface preparation will allow the build-upof a bacteriologically active layer in the schmutzdecke which will eliminate theexceedance of the total coliform standard. The exceedances of the color and odorstandard may persist. While the filtration process clearly reduced the concentrations ofboth compounds in the water from the wetland system, it did not reduce them enough tomeet the SDWS.

The investigators discussed and considered the issues related to endocrinedisrupting chemicals (EDC), Pharmaceuticals, and Personal Care Products (PPCP).Several approaches were considered to incorporate possible research in this project. Atthe time this project was funded, however, the USGS and the USEPA were still in theprocess of establishing sampling and analytical protocols. This consideration along withthe fact that the purpose of the study was to investigate if natural processes could produce

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water meeting the drinking water standards, which did not and still do not incorporateEDC / PPCP criteria, were the reasons not to incorporate any EDC / PPCP work into thePilot Study.

The temperature of the warmer water from the cooling pond and effluent inflow

into the wetland was reduced on an average by 5.4C (9.7F) while flowing through thewetland with a maximum difference of 8.5C (15.3F). The temperature increasedslightly by an average of 1.3C (2.3F) during filtration through the tailing sand filterbasin. The average net difference in temperature of the water flowing into the wetlandand the treated and filtered water flowing from the filter basin is 3.9C (7.0F), with amaximum difference of 9.8C (17.6F).

During the wet season, the rainfall captured between the two dams on either sideof the linear wetland would provide an additional source of water to the wetland. Thisaction had a diluting effect on the water in the wetland and in the filter basin. This isreflected in the record on the chloride concentrations, particularly during the period when

water from the cooling pond was being used as source water. The average chlorideconcentration flowing into the wetland was 105 mg/l. The average chlorideconcentration in the water pumped from the wetland was 89 mg/l, while the averageconcentration in the water pumped from the filter basin was 76 mg/l. Similarly, when theeffluent was used as a source, the average concentrations were 94, 74, and 71 mg/lrespectively in the effluent, wetland and filter basin water.

The concentrations of sulfate in the surface water were reduced to a larger extentthan could be accounted for by dilution with rainfall. In addition, the pH of the coolingpond water was reduced by approximately 2 units during the flow through the wetland,indicating a reducing environment. This, in combination with the hydrogen sulfide odorcoming from the wetland water being delivered to the surface of the filter basin, leads toa qualitative observation that sulfate in the water flowing into the wetland is most likelybeing reduced to sulfide by anaerobic bacteria in the wetland in the presence of organicmatter. No field data were collected to determine the sulfide concentration in the waterpumped from the wetland or in the water pumped from the basin. In addition to thisobservation, it is reasonable to infer a correlation between hydrogen sulfide smell and theodor measurements. If this correlation holds, then the odor data suggest that the waterpumped from the basin may also be in a reducing state because the average odorconcentration in the cooling pond water was 30 TON (Threshold Odor Number), in thewetland water 80 TON, and in the basin water 42 TON. Recharging water low ordepleted in oxygen and in a reducing state will reduce the probability or prevent thedissolution of metals from the limestone matrix.

The present natural treatment system at the Hines Energy Complex site ofProgress Energy of Florida can be easily adapted to use the water for differentapplications. The initial purpose of the natural treatment system was to investigate if theindustrial wastewater from the cooling pond and the treated effluent from the City ofBartow could be treated to such an extent that this water could be recharged to theunderlying Floridan Aquifer. This pilot study has documented that allprimary drinking

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water standards were met all the time except for total coliform. Five secondary standardswere exceeded from time to time. However, the Department of Environmental Regulationcan and will allow exemptions for exceedances of secondary drinking water standards.The only remaining issue for the use of this water for recharge to the Floridan Aquifer isthe compliance with the total coliform criterion. There is ample evidence from projects in

this area that treatment of the water from the filter basin with ultraviolet light will bringthis criterion into compliance. From the data that we have, we do not know of anylimitations of this system except for the microorganism issue described above. As statedbefore this limitation can be easily overcome with the use of ultra-violet light treatmentof the filtered water.

No range of costs to implement a natural treatment system was evaluated in thisproject. However, a previously published report by FIPR (Publication number 03-113-186), which is referenced above, provides several cost estimates for five proposedprojects in the mining areas. According to that report, a total of 84 million gallons perday could be recharged to the Floridan Aquifer at an average unit cost of $1.10 per 1000

gallons. UV treatment was not considered in the conceptual engineering plans and costestimates in the earlier study.

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INTRODUCTION

This pilot project is part of a multi-stage research plan that involves the treatmentof industrial wastewater from a cooling pond used by an electric power generating plant,as well as tertiary treated effluent and surface waters by treatment through natural

processes on reclaimed lands previously mined by phosphate mining companies. Thebasic concept on which this project rests is the assumption that natural systems, inparticular wetlands created on reclaimed waste clay settling areas (CSAs) followed bytailing sand filtration, will remove any organic, inorganic and microbiologicalcontaminants in surface (storm) waters, industrial wastewaters, and domesticwastewaters. While a significant body of information exists on the capacity of wetlandsto treat effluent to meet the NPDES standards, information on the capacity of wetlands onreclaimed CSAs followed by tailing sand filtration to remove these contaminants to suchan extent that Primary and Secondary Drinking Water Standards (PDWS/SDWS) can bemet is limited. The purpose of this pilot study was to fill this lack of information on thefeasibility of the concept by using an existing wetland and by constructing a tailing sand

filter basin (hereafter referred to as basin) at the Hines Energy Complex (hereafterreferred to as Hines) in Polk County, which is owned and operated by Progress EnergyFlorida. In addition to the construction of the tailing sand filter basin, pumping stationsand pipelines were built to transport treated effluent, storm water, and industrialwastewater to the site.

After the infra-structure was built, an intensive two year water quality samplingand assessment project was completed to evaluate if this natural treatment system cansafely and effectively recondition different types of surface waters, industrialwastewaters, and domestic wastewaters to meet the Florida Department of EnvironmentalProtection and States drinking water standards. The Florida Institute of Phosphate

Research (FIPR) and the Southwest Florida Water Management District (SWFWMD)funded the project in equal parts. The ultimate goal of the overall project was a completeassessment of the feasibility to use this natural treatment process in combination withrecharging the treated water to the underlying Upper Floridan Aquifer to use the aquiferas a temporary surface water storage reservoir without incurring evaporative losses, whileat the same time increasing the overall regional water availability by capturing flood andstorm waters. This pilot project is the first part of a larger project, which also includesthe construction of a recharge well at Hines and the subsequent testing of the concept byrecharging the naturally treated water through this well during the one year testing of theAquifer Recharge and Recovery Project (ARRP) well.

PURPOSE AND OBJECTIVES OF CURRENT INVESTIGATION

The purpose of the pilot test was to evaluate the feasibility of using naturalprocesses under controlled conditions to purify surface and wastewater to meet drinkingwater standards. The original mandate for this project was to use three kinds of water totest this concept, namely water from the cooling pond (industrial waste water), tertiarytreated effluent (domestic waste water) from the City of Bartows wastewater treatmentplant, and surface runoff (storm water) from the water cropping areas on the property.

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Because of time constraints resulting from operational difficulties, it was decided to focusprimarily on the cooling pond water and effluent. No surface water runoff (storm water)was used as a source.

Construction of the project started in March 2000. The water quality samplingphase of the pilot project started in May 2001. The system operated from May 2001

through December 2001 with water from the cooling pond as the initial water source.Significant changes and modifications were made to the system between January and Julyof 2002. One of the major actions during that time was the disinfection of the entire filterpiping and standpipes using chlorine. This process was followed by redevelopment ofthe filter piping by high-pressure backwashing and pumping. The delay occurred in thatadditional funding was requested for this work, which had to be approved by theGoverning Boards of FIPR and the SWFWMD. The system was restarted in August2002.

The system ran more or less continuously from August 2002 through March 2003with water from the cooling pond as the water source. The cooling pond water is a

mixture of storm water and treated effluent subjected to heating and cooling as well asevaporative losses. From April 2003 through December 2003, the system rancontinuously with tertiary treated effluent as the water source until its shutdown inJanuary 2004. The tertiary treated effluent (from here on referred to as effluent) wastransported to the site via an existing pipeline along the east side of Hines. The third typeof water (storm water) was to be transported from the water cropping areas on theproperty. These water-cropping areas are essentially CSAs, where rainfall is capturedand directed to the cooling pond to replace the evaporative losses. Although this sectionof the pilot test was not performed due to issues with operational system, equipmentrepairs, and excessive rainfall, conclusions can still be made regarding the effectivenessof the treatment system.

LOCATION OF PROJECT AREA

The project was located at Progress Energy Floridas (PEFs) Hines EnergyComplex to the southwest of the City of Bartow in Polk County in Florida as seen inFigure 1. The Hines site was built on previously mined land in Polk County, southwestof Bartow, Florida, located on County Road 555, just south of State Road 640.

The project was a pilot test for much larger systems that can be implemented atseveral locations around the area. The ARRP concept was developed as a result of a

previous FIPR Study (Publication No. 03-113-186) entitled Feasibility of NaturalTreatment and Recharge of Waste Water and Surface Waters using Mined PhosphateLands, A Concept to Expand Regional Water Resource Availability. In this study a totalof five project sites were identified where the ARRP concept could be implemented andthe construction, operating, and maintenance costs were estimated for each project. Thelocations of the five project sites are shown in Figure 2. The pilot test provides thenecessary design data to implement the concept at several locations within the BoneValley phosphate-mining district.

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Figure 1. General Location of Progress Energy Floridas Hines Energy Complex

with Surrounding Areas.

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Figure 2. General Location of the Bone Valley Phosphate Mining District and theProject Sites.

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SELECTION OF LOCATION OF THE PROJECT AREA

To select the location of the site for implementing the pilot study, Dr. Richardsonand the Principal Investigator initially determined the criteria for the selection of a site.One of the key criteria for the selection of a site was the availability of three different

types of water. The three types of water were storm water, treated or untreated effluent,and industrial wastewater. The second major criterion was the size of the system. Whilemany clay-settling areas were possibly available, the size of the treatment area had tomatch the other testing constraints such as the size of the tailing sand filter basin to beconstructed, the pumping rate, and the anticipated retention time within the wetlandsystem.

After repeated field visits to several areas, a potential site was identified at Hines,which is owned and operated by PEF. This site came to the attention of the project teambecause PEF was interested in the ARRP concept as a means of creating additional long-term water storage for the capture of storm water from their water cropping areas

(WCAs).

The Hines site occupies over 8,200 acres of previously mined phosphate land.This includes 900 acres of power generating and ancillary facilities, a 722-acre coolingreservoir, 2,000 acres that serve as buffer areas along the east and southeast portions ofthe site, and 520 acres along the west and southwest portions of the site that remainundeveloped and act as a wildlife preserve. A detailed map of the Hines site is presentedin Figure 3.

The site selected for the pilot project at Hines consisted of two parallel ditchesbetween two CSAs. One ditch (the larger one) was a return ditch for water from the N-15

CSA. The other (the smaller one) was initially constructed to collect toe drain seepagefrom the SA-8 CSA dam. To connect the two ditches hydraulically, a breach was dug inthe berm separating the ditches. This connection is approximately 4000 feet to the westof the cooling pond. The location and layout of the ditches is presented in Figure 4. Theditches always contained surface water, and vegetation normally associated with wetlandsystems common to CSAs colonized both ditches (i.e., water hyacinths, water lettuce,babys tears, cattails, dog fennel, and willows). The ditch system is considered a linearwetland system with a total length of approximately 8000 feet, an average width ofapproximately 25 feet and a depth of water ranging from 3 to 4 feet in the northern ditchand from 1.5 to 2.5 feet in the southern ditch. For the remainder of this report the twoconnected ditches will be identified as the wetland.

The original concept of the pilot project set-up is shown in Figure 5. It wasplanned to excavate the eastern end of the ditch system to construct the tailing sand filterbasin (hereafter referred to as the basin). After a detailed investigation, SI wasinformed that the N-15 dam was constructed with a sand drainage blanket. This sanddrainage blanket drains towards the wetland, and therefore, the construction of a linedbasin would have interfered with the draining function of the sand blanket. In addition, itwas clear that constructing the basin could have also interfered with the toe of the damcontaining the cooling pond. For these reasons it was decided to construct the filter basin

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at another location. This significantly increased the initially estimated cost of the projectbecause of the additional pipe conveyance system that had to be built.

Two locations were considered for the construction of the basin. The first onewas at the northwest corner of the SA-8 CSA. The second one was at the northeast

corner of the N-11B CSA. The locations of both sites are shown in Figure 6. A soil-boring program was conducted at both sites. Based on the findings of this program, adecision was made to construct the basin at the northwest corner of SA-8. At bothlocations, the tailing sand was deposited on top of waste clays and mud waving hadoccurred resulting in an uncertainty where to find and mine clean (unmixed) sandtailings. At the SA-8 site, SI implemented a detailed soil exploration to map the depthand horizontal extent of the sand tailings deposits. The result of the soil boring surveywas that SA-8 contained a sufficient quantity of clean unmixed sand tailing at the surfaceto construct the basin.

Figure 3. Detailed Map of the Hines Energy Complex.

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Figure 4. Detailed Map of Ditches.

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Figure 5. Original Concept of Pilot Project Set-Up.

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Figure 6. Map of the Two Tailing Sand Deposits at SA-8 and N-11B.

PROJECT HISTORY

A timeline of events beginning in 2000 and ending in 2004 is presented in Table1. The initial meetings, planning, and testing occurred in the early part of the year 2000,followed by extensive construction to build the filter basin and pumping systems for theremainder of the 2000 and the beginning of 2001. The first testing phase of the wetland-filter basin treatment system began in May of 2001. In the summer of 2001, fish remainswere found near the piping and it was conjectured that birds consuming fish whileperched on the piping coming out of the two standpipes at the basin had contaminated thefilter piping system with microorganisms in their fecal matter. To remedy this situation,

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SI requested and received additional funding to clean and disinfect the filter piping andstandpipes. This phase was completed in June 2001. From that time, the system rancontinuously through the end of the year. After an initial assessment of the project anddata, there were several modifications made to the system, which were completed in thesummer of 2002. The treatment system ran from August 2002 to March of 2003 with the

cooling pond as the water source, and then from April 2003 to December 2003 with theeffluent as the water source. During this time, a series of issues arose, such as equipmentfailures, climatic events, and operational problems. Problems with the equipment includefaulty wiring and installations, defective equipment, and phase and power fluctuations.Lightning, excessive rain, and wildlife were uncontrollable events that were dealt with asbest as possible. Operational problems consisted of differing water levels in the filterbasin causing the water level float control system to work inconsistently, the major causeof the wetland filter basin treatment system shutting down.

A detailed time and event log of this project is presented in Appendix A.

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Table 1. Timeline of 2000 through 2004.

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DESIGN AND CONSTRUCTION OF TREATMENT SYSTEM

PROJECT CONFIGURATION

The overall project configuration is shown in Figure 7. It consists of seven

pumping stations: at the wetland, the basin, the cooling pond, the SA-8 CSA, the PlantIsland drainage ditch, and at the effluent discharge pipe into the cooling pond. At eachlocation, electrical power was provided by PEF to electrical panels, which were installedalong with control systems. At the wetland, basin, cooling pond and effluent location,7.5 HP electrically-driven centrifugal pumps, each with a 240-260 gallon per minute(gpm) capacity at 60-70 pounds per square inch (psi) total dynamic head were installed.In addition, continuously recording flow meters were installed. The water pumped fromthe cooling pond, SA-8, the Plant Island drainage ditch and Effluent Discharge pipe wereall routed to discharge to the east side of the north ditch of the wetland through a 4-inchdiameter HDPE pipe or larger. Similarly, the wetland pumping station was connected tothe basin through a 4000 ft long 4-inch diameter HDPE pipeline. The water pumped

from the basin was discharged to the cooling pond through a 4500 ft long 4-inch diameterHDPE pipeline.

DESIGN OF INDIVIDUAL PROJECT ELEMENTS

As previously described, the selection of the final project configuration dependedon the selection of the final location of the tailing sand filter basin. After the project wasauthorized and field inspections were conducted in consultation with the PEFrepresentatives, it was determined that the concept as originally envisioned for the filterbasin could not be built; alternative ideas were therefore explored. One choice was to

construct the filter basin at the nearest tailing sand deposits, which were at the northwestcorner of the SA-8 CSA. SI conducted a test boring program to evaluate the feasibility ofusing this tailing sand deposit as an in-situ filter bed. This was not found to be feasibledue to the interlayer of clays with the sand. A similar exploration program wasconducted at the tailing sand deposits at N-11C CSA. The results were that this site alsocould not be used as a tailing sand filter in the as is condition. After much deliberation,it was decided that since neither site was viable as is, SI would design and construct atailing sand filter basin at the SA-8 CSA site using the tailing sand that was on-site.

There was never a problem for the use of the two ditches as the linear wetland.There was however, a discussion followed by a field visit to assess the need for the

improvement of the wetland by removing invasive species and replacing these withnative wetland vegetation. After much debate, a consensus was reached that thevegetation as it appeared in the linear wetland is representative of the vegetation that canbe expected to occur in clay settling areas after they are no longer in operation and havebeen drained. Therefore, the vegetation remained unmodified.

A detailed description of the design steps and selection of the equipment ispresented in Appendix B.

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Figure 7. Final Systems Map.

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CONSTRUCTION OF INDIVIDUAL PROJECT ELEMENTS

There were three major construction elements to the project: (1) the constructionof the tailing sand filter basin; (2) the construction of the wetland filter and pumpingintake structure; and (3) the installation of approximately 22,000 linear feet of 4-inch

diameter HDPE pipeline and 5 pumping stations with the associated electric powersupplies, flow meters and valving. A detailed description of the construction elements isprovided in Appendix C.

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Table 2. Number of Samples Collected.

Water

Source

Sample

Location

Performance

Standards PDWS SDWS

VolatileOrganic

Contami-nants

SyntheticOrganic

Contami-nants

Group I

Unreg-ulated

Group II

Unreg-ulated

GroupIII

Unreg-ulated

C

CoolingPond 22 6 6 4 4 4 4 4

Wetland 22 6 6 4 4 4 4 4 Cooling

Pond

Basin 22 7 10 4 4 4 4 4

Effluent 7 12 12 12 12 12 12 12

Wetland 7 11 11 11 11 11 11 11 Effluent

Basin 7 12 12 12 12 12 12 12

Total # of Samples* 87 54 57 47 47 47 47 47

* Does not include measurements of the physical parameters.23

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The results are summarized and presented in Tables 3 through 11. These tableslist all the parameters in the PDWS (Table 3); in the SDWS (Table 4); in the VolatileOrganic Compounds (Table 5); in the Synthetic Organic Compounds (Table 6); in theGroup I Unregulated Compounds (Table 7); in Group II Unregulated Compounds (Table8); in the Group III Unregulated Compounds (Table 9); the Microorganisms (Table 10);

and the Radionuclides (Table 11). The name of each chemical compound is shown, alongwith the number of samples that were collected and the number of samples that exceededthe recommended drinking water standards. In the data appendices, the drinking waterstandard value for each compound (where applicable) has been listed along with thedetection limit.

The tables illustrate there were no exceedances of the PDWS for any of thechemical compounds listed. There were no exceedances for the Volatile OrganicCompounds, the Synthetic Organic Compounds, the Group I, II or III UnregulatedCompounds and none for the radionuclides. There were, however, exceedances of therecommended SDWS as shown in Table 4. Of the 14 listed parameters, 6 exceeded the

recommended SDWS. They were for Aluminum (1/18); Fluoride (22/44); Iron (36/44);Manganese (20/44); Color (18/18); and Odor (16/18). Other exceedances were forconcentrations of Microorganisms (Table 10), with Fecal Coliform (4/30) and TotalColiform (34/65).

The measurements of the physical parameters (such as the specific electricalconductance, pH and temperature), turbidity, flow and electric meter readings arepresented in Appendix I (Table I-1, Table I-2, Table I-3 and Table I-4). The physicalparameters show several interruptions in the data collection caused by inaccessibilityeither of the instruments and/or by malfunction. The turbidity of the water pumped fromthe cooling pond, the effluent, the wetland and the basin was measured regularly. Theresults are presented in Table I-3. The first instrument used for turbidity measurementswas not sensitive enough, so on February 21, 2003, SI purchased a new instrument. Thisis the reason the information in Table I-3 appears different after February 2003.

In February 2003, SI expanded the data collection system for the basin. Thehypothesis was that groundwater from outside the basin was entering the basin, mostlikely along its southern periphery. This seepage groundwater was assumed to containhigher iron concentrations because it was intercepted primarily by the filter pipe in thesouthern part of the basin, which is connected to the SS, and the SS water had muchhigher iron concentrations. To assess this hypothesis, SI implemented a more elaboratemeasurement and sampling program by collecting samples from the NS and SSseparately. The collected data are summarized in Table I-6.

During the data analysis phase of the project after December 2003, SI realizedthat it would be helpful to obtain additional information regarding the infrequentexceedances of the concentrations of Total Coliform bacteria. The literature indicatesthat the formation of a layer of mostly organic matter on the surface of the sand will aidin the reduction of the concentration of total coliform bacteria. This is called theschmutzdecke or dirt layer. Because of the periodic operation of the wetland pump, the

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formation of an effective schmutzdecke on the surface of the filter basin was notoptimized. To gather quantitative bench test data about the possible relationship betweenthe formation of a schmutzdecke, the reduction of the total coliform bacteria count, andthe reduction of the effective vertical hydraulic conductivity, SI created a field testingoperation at its field office.

A description of the test set-up, photographs and results of the field-testing arepresented in Appendix J.

Table 3. Samples and Exceedances for Primary Drinking Water Standards.

Primary Drinking Water Standards

Parameter PDWSNumber of

SamplesNumber ofExceedances

Antimony 0.006 mg/L 15 0

Arsenic 0.05 mg/L 15 0Asbestos 7 million fibers/L 6 0

Barium 2 mg/L 15 0

Beryllium 0.004 mg/L 15 0

Cadmium 0.005 mg/L 15 0

Chromium 0.1 mg/L 15 0

Cyanide 0.2 mg/L 13 0

Fluoride 4.0 mg/L 44 0

Lead 0.015 mg/L 15 0

Mercury 0.002 mg/L 15 0

Nickel 0.1 mg/L 15 0

Nitrate 10 mg/L as Nitrogen 14 0

Nitrite 1 mg/L as Nitrogen 14 0

Total Nitrate and Nitrite 10 mg/L as Nitrogen 14 0

Selenium 0.05 mg/L 15 0

Sodium 160 mg/L 15 0

Thallium 0.002 mg/L 15 0

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Table 4. Samples and Exceedances for Secondary Drinking Water Standards.

Secondary Drinking Water Standards

Parameter SDWS

Number of

Samples

Number of

ExceedancesAluminum 0.2 mg/L 18 1

Chloride 250 mg/L 18 0

Copper 1.0 mg/L 18 0

Fluoride 2.0 mg/L 44 22

Iron 0.3 mg/L 44 36

Manganese 0.05 mg/L 44 20

Silver 0.1 mg/L 18 0

Sulfate 250 mg/L 44 0

Zinc 5.0 mg/L 18 0

Color 15 CU 18 18

Odor 3 TON 18 16pH 6.5-8.5 44 0

Total Dissolved Solids 500 mg/L 18 0

Foaming Agents 0.5 mg/L 18 0

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Table 5. Samples and Exceedances for Volatile Organic Compounds.

Volatile Organic Compounds

Parameter MCLNumber of

SamplesNumber ofExceedances

1,1-Dichloroethylene 0.007 mg/L 12 01,1,1-Trichlororethane 0.2 mg/L 12 0

1,1,2-Trichloroethane 0.005 mg/L 12 0

1,2-Dichloroethane 0.003 mg/L 12 0

1,2-Dichloropropane 0.005 mg/L 12 0

1,2,4-Trichlorobenzene 0.07 mg/L 12 0

Benzene 0.001 mg/L 12 0

Carbon tetrachloride 0.003 mg/L 12 0

cis-1,2-Dichloroethylene 0.07 mg/L 12 0

Dichloromethane 0.005 mg/L 12 0

Ethylbenzene 0.7 mg/L 12 0

Monochlorobenzene 0.1 mg/L 12 0O-Dichlorobenzene 0.6 mg/L 12 0

para-Dichlorobenzene 0.075 mg/L 12 0

Styrene 0.1 mg/L 12 0

Tetrachloroethylene 0.003 mg/L 12 0

Toluene 1 mg/L 12 0

trans-1,2-Dichloroethylene 0.1 mg/L 12 0

Trichloroethylene 0.003 mg/L 12 0

Vinyl chloride 0.001 mg/L 12 0

Xylenes (total) 10 mg/L 12 0

m/p-xylenes 0.5 g/L (DL) 12 0

o-xylene 0.5 g/L (DL) 12 0

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Table 7. Samples and Exceedances for Group I Unregulated Compounds.

Group I Unregulated Compounds

Parameter DLNumber of

SamplesNumber ofExceedances

3-Hydroxycarbofuran 0.5 g/L 12 0Aldicarb 0.5 g/L 12 0

Aldicarb sulfone 0.5 g/L 12 0

Aldicarb sulfoxide 0.5 g/L 12 0

Aldrin 0.08 g/L 12 0

Butachlor 0.06 g/L 12 0

Carbaryl 0.5 g/L 12 0

Dicamba 0.25 g/L 12 0

Dieldrin 0.06 g/L 12 0

Methomyl 0.5 g/L 12 0

Metalachlor 0.05 g/L 12 0

Metribuzin 0.1 g/L 12 0Propachlor 0.07 g/L 12 0

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Table 8. Samples and Exceedances for Group II Unregulated Compounds.

Group II Unregulated Compounds

Parameter DLNumber of

SamplesNumber ofExceedances

1,1,1,2-Tetrachloroethane 0.3 g/L 12 01,1,2,2-Tetrachloroethane 0.3 g/L 12 0

1,1-Dichloroethane 0.3 g/L 12 0

1,1-Dichloropropene 0.3 g/L 12 0

1,2,3-Trichloropropane 0.3 g/L 12 0

1,3-Dichloropropane 0.3 g/L 12 0

1,3-Dichloropropane, Total 0.3 g/L 12 0

2,2-Dichloropropane 0.3 g/L 12 0

Bromobenzene 0.5 g/L 12 0

Bromodichloromethane 0.3 g/L 12 0

Bromoform 0.5 g/L 12 0

Chloroethane 0.5 g/L 12 0Chloroform 0.2 g/L 12 1

Chloromethane 0.5 g/L 12 0

Dibromochloromethane 0.5 g/L 12 0

Dibromomethane 0.5 g/L 12 0

Dichlorodifluoromethane 0.5 g/L 12 0

m-Dichlorobenzene 0.5 g/L 12 0

Methyl-tert-butyl-ether 0.5 g/L 12 0

o-Chlorotoluene 0.5 g/L 12 0

p-Chlorotoluene 0.5 g/L 12 0

Trichlorofluoromethane 0.5 g/L 12 0

Table 9. Samples and Exceedances for Group III Unregulated Compounds.

Group III Unregulated Compounds

Parameter DLNumber of

SamplesNumber ofExceedances

2,4,6-Trichlorophenal 0.8 g/L 12 0

2,4-Dinitrotoluene 3 g/L 12 0

2-Chlorophenol 1 g/L 12 0

4,6-Dinitro-o-cresol 1 g/L 12 0

Butylbenzylphthalate 2 g/L 12 0Diethylphthalate 1 g/L 12 0

Dimethylphthalate 1 g/L 12 0

Di-n-butylphthalate 2 g/L 12 0

Di-n-octylphthalate 2 g/L 12 0

Isophorone 2 g/L 12 0

Phenol 0.8 g/L 12 0

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Table 10. Samples and Exceedances for Microorganisms.

Microorganisms

Parameter DWSNumber of

SamplesNumber ofExceedances

Fecal Coliform 0 MPN/100mL 30 4Total Coliform 4 MPN/100mL 65 34

Cryptosporidium 0 detected/100mL 6 0

Giardia 0 detected/100mL 6 0

Table 11. Samples and Exceedances for Radionuclide Contaminants.

Radionuclide Contaminants

Parameter DWSNumber of

SamplesNumber ofExceedances

Gross Alpha 15 pCi/L 42 0

Radium 226 5pC/L 42 0Radium 228 5 pCi/L 42 0

DISCUSSION

In this part of the report, the focus is on the operational aspects of the system andhow it relates to the performance of the treatment system in improving the quality of theinfluent source water.

Performance Assessment

The purpose of the pilot study was to evaluate the use and effectiveness of thetreatment capacity of a wetland on mined phosphate land followed by filtration throughtailing sand. The success or failure of such a system can be determined in two ways: 1)by looking at the chemical analytical results of the filtered water and comparing these tothe published standards and 2) the changes in concentrations of chemical compounds inthe source water while flowing through the wetland and filter basin.

The first assessment of the overall performance has been discussed previously.The outcome is that of the 140 physical and chemical parameters tested for, exceedances

of only six regulatory standards (SDWS) occurred. This section discusses the changesthat were observed in the water during the flow through the treatment system. Thecapacity of the system is further evaluated by comparing its performance for treatingindustrial wastewater from the cooling pond to its performance for treating effluent fromthe City of Bartow wastewater treatment plant.

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Physical Parameters

The physical parameters of interest are the total volume of water treated, rainfall,pH, specific electrical conductance, temperature, turbidity, color, odor and total dissolvedsolids.

Volume Pumped

There is uncertainty about the volume of water that was pumped during the life ofthe project from each source into the wetland and from the wetland to the filter basin andfrom the filter basin to the cooling pond. To save costs, an existing pump installed byPEF for a previous test was used to move the water from the cooling pond to the wetland.Similarly, an existing pump (Randys pump) was used to pump water from the wetlandback to the cooling pond. Neither flow meters nor electric meters were installed on thesepumps. Based on operational logs the pumpage record from the basin, wetland and

effluent pumps show many interruptions by either a partial blockage in the flow meter oran electrical interruption caused by lightning or by a power surge or phase change.

According to the flow meter records presented in Appendix I, Table I-4, a total ofapproximately 151 million gallons (MG) were pumped from the basin and returned to thecooling pond. A total of approximately 77 MG were pumped from the wetland to thefilter basin. There is no record of the total pumpage from the cooling pond to thewetland. There is a record of the total pumpage from the effluent to the wetland (35MG). An assessment of the most complete record during the time when the effluent wasused as a source, estimates that a total of 35 MG of effluent was discharged to thewetland. During that same time interval, 20 MG were pumped to the basin from thewetland, and approximately 46 MG were pumped from the basin to the cooling pond.The numbers vary quite significantly because the meters sometimes malfunctioned anddid not always accurately register the flow.

A slightly better indication of the total water moved from the effluent to thewetland and from the wetland to the basin and from the basin to the cooling pond is theelectric meter record in kw/hr. The total amount for the effluent was 18,813 kw/hr. Forthe wetland it was 13,735 kw/hr and for the basin 20,391 kw/hr. While these numbersappear to be closer, care needs to be exercised in their interpretation. For example, thebasin pump has to lift the water from a depth that ranged from 2 to 13 feet below pumpintake, and averaged approximately 8 feet. The deeper the groundwater level below thepump intake the lesser the volume of water the surface centrifugal pump will displace.The result is that more energy is needed to displace the same volume of water from agreater depth.

If the meters were most accurate at the beginning of the operation, the volume ofwater pumped per kw/hr used was calculated. They were 2,517, 1062 and 1679 g/kw/hrrespectively. Using these values and the difference between the electric meter readingwhen the effluent operation began, SI estimates that 47.4 MG of effluent were pumped to

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The median pH was 6.88 in the basin, 6.85 in the NS of the basin and 6.88 in theSS of the basin. The median pH of the wetland water percolating through the filter basindeclined slightly from 7.14 to 6.88, indicating a continuation of the reducing conditionsobserved in the wetland. This effect was most pronounced when cooling pond water wasthe source.

Figure 9 shows the rainfall measured at the basin against time, along with the pHmeasurements at the wetland and the basin. It is interesting that the reduction of the pHdoes not seem to be greatly influenced by the rainfall, which totaled approximately 158inches for the entire study period. This amounts to an input of 4.9 MG onto the totalsurface area of the filter basin.

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pH vs. Rain in the Basin, Wetland, Cooling Pond, and Effluent ov

0

2

4

6

8

10

12

5/1/2001

6/1/2001

7/1/2001

8/1/2001

9/1/2001

10/1/2001

11/1/2001

12/1/2001

1/1/2002

2/1/2002

3/1/2002

4/1/2002

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11/1/2002

12/1/2002

1/1/2003

2/1/2003

3/1/2003

4/1/2003

5/1/2003

6/1/2003

Time

pH

Basin Wetland Cooling Pond Effluent Rain

Date of S

Switch 4/

Figure 9. pH and Rainfall Over Time.

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Specific Electrical Conductance versus Rain in the Basin, Wetland, Cooling P

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Figure 10. Specific Electrical Conductance and Rain Over Time.

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Figure 11. Temperature Over Time.

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In addition, there is a reduction in temperature of the source water flowingthrough the wetland. The decrease in temperature of the surface water in the wetland isattributed to the shade provided by the vegetation preventing solar heating of the surfacewater in the wetland. The difference between the temperature of the surface water beingdischarged from the cooling pond or the effluent to the wetland and the temperature of

the water being pumped from the basin ranged form a high of 9.6C to a low of -2C.The median difference is 3.9C. The greatest seasonal change of 17.7C in the wetlandoccurred between September 30, 2002 and January 24, 2003.

The treatment system reduced the median temperature by approximately 15%.When the effluent was used as a source the drop in median temperature was 3.8C (6.8

F) or 13%.

Comparing these median values leads to the conclusion that the treatment systemreduces surface water temperatures significantly. Although no solar radiationmeasurements were taken as part of this project, the data clearly suggest that the largest

temperature drop occurred in the wetland. This leads to the observation that thevegetative cover in the wetland system prevented direct solar radiation of the watersurface, thereby preventing heat build-up in the surface water. This observation leads tothe question if clay-settling areas with large vegetated surfaces would be useful or evenpractical alternatives to the open water cooling ponds. Not calculated as part of thisproject is the total reduction in heat load for an average pumping rate of 150 gpm and amedian drop in temperature of 3.9C (6.8F).

Turbidity

The measurement of turbidity provides an indicator of the effectiveness of thefilter media. The turbidity data are presented in Table I-3. As mentioned previously, amore sensitive turbidity meter was purchased in February 2003. This is reflected in thedata in Table I-5. The information presented in this section applies to the data that werecollected and recorded since February 2003.

The median values of turbidity for the water from the cooling pond was 7.5Nephelometric Turbidity Units (NTU), for the effluent it was 1.7, for the wetland 2.0NTUs and for the basin 1.65 NTUs. For the same waters the ranges from minimum tomaximum were 0.0 to 25.3 NTUs (cooling pond); 0.4 to 10.3 NTUs (effluent); 0.1 to 15.0NTUs (wetland) and 0 to 413 NTUs (filter basin). The high value at the filter basin is

most likely because a change in the pumping regime may have caused IRB biofilmsludge in the filter pipe to be loosened and to be pumped out.

In general, the turbidity in all three water sources is low. This has been apparentin the operation of the filter basin. During its operational life, it was anticipated in thesurface distribution design that high turbidity from suspended solids in the water pumpedfrom the wetland would cause significant reductions in the surface hydraulicconductivity. This assumption was because the wetland could be producing algal growth

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Of note is the fact that the median odor concentration in the effluent discharge ismore than twice as high as in the cooling pond. The reducing environment in the wetlandincreases the median odor concentration more than fourfold when the cooling pond wateris used as a source. The median odor concentration in the wetland actually declines from50 TON to 35 TON when the effluent is used as a source. Based on field observations by

SI personnel, the wetland water discharging to the surface of the tailing sand filter basinproduced an unmistakable and strong hydrogen sulfide odor. The median sulfateconcentration in the cooling pond water is 110 mg/l, whereas the median concentration inthe effluent is 50 mg/l. SI hypothesizes that the reduction of sulfate ions bymicroorganisms results in the hydrogen sulfide odor. With a lesser supply of sulfate inthe wetland when effluent is used, the capacity to generate odor is diminished.

Total Dissolved Solids

The SDWS for total dissolved solids (TDS) is 500 mg/l. In the cooling pond, the

SDWS was exceeded in every sample. The median value was 520 mg/l and ranged from510 to 530 mg/l. When the cooling pond water was used as a source, the TDS in thewetland was in exceedance of SDWS in two of the nine samples. The median TDS valuewas 430 and ranged from 260 to 570 mg/l. The TDS concentrations in the water from thebasin never exceeded the SDWS. The median value was 360 and the concentrationsranged from 250 to 500 mg/l.

The TDS SDWS was not exceeded in samples from the effluent discharge,wetland, or basin. In the effluent discharge, the median TDS concentration was 295 mg/lranged from 270 to 440 mg/l. In the wetland, the median TDS concentration was 280mg/l and ranged from 180 to 490 mg/l. In the filter basin, the median TDS was 255 mg/land ranged from 180 to 440 mg/l.

The decline in the median TDS concentrations between the cooling pond water asa source and the water discharging from the basin was 31%. This same percentagereduction was observed in the measurements of the SEC. The decline in the median TDSconcentration when the effluent was used as a source, between the effluent and the waterdischarging from the basin was 14%. This number is somewhat higher than that for theSEC under the same circumstances (14 versus 9), but could still be interpreted as asimilar occurrence.

Inorganic Chemicals

The inorganic chemicals of interest are iron, manganese, fluoride, sodium, sulfateand chloride. While there were no exceedances reported for sodium, chloride and sulfate,a comparison of the change in concentrations of these chemicals is an indication of animportant function of the system while the water is moving through the treatment system.

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Iron and Manganese

There were two sets of data collected. The first set were field measurementsusing a field test kit, the second set were the concentrations determined by a laboratory.In the following paragraphs, SI used the information obtained from the laboratory

analyses only. The SDWS for iron is 0.3 mg/l and for manganese 0.05 mg/l. It isimportant to note that the sampling location in the basin changed from collecting groundwater from both NS and SS combined to only from NS. This change in samplingprotocol occurred on May 22, 2003.

During the period when the cooling pond was the source water, ironconcentrations in the cooling pond were present in 23 of the 25 samples and ranged from0.02 to 0.12 mg/l, with a median value of 0.04 mg/l, which does not exceed the SDWS.Manganese was present in all but three of the 25 samples dates with concentrationsranging from 0.01 to 0.02 mg/l, with a median value of 0.01 mg/l, well below the SDWS.In the wetland, iron was detected in all 25 samples, ranging from 0.05 to 0.26 mg/l, with

a median value of 0.14 mg/l, which does not exceed the SDWS. Manganese was presentin all 25 samples ranging from 0.01 to 0.07 mg/l, with a median value of 0.03, which isbelow SDWS.

In the basin, iron was detected in all 26 samples and ranged from 0.48 to 4.7 mg/l,with a median value of 1.15 mg/l. The iron concentrations in the basin samples exceededSDWS for all 26 samples. Manganese was detected in all 26, with 20 samples exceedingstandards. The concentrations ranged from 0.02 to 0.11 mg/l, with a median value of0.07 mg/l.

When the effluent was used as the source, iron was detected in all 24 effluentdischarges, wetland, and basin samples. In the effluent discharge, iron concentrationsranged from 0.042 to 0.49 mg/l, exceeding SDWS in only one sample. The medianconcentration was 0.08 mg/l. Manganese was present in 20 of 25 samples withconcentrations ranging from 0.01 to 0.08 mg/l with two samples exceeding the SDWS.The median concentration was 0.03 mg/l.

In the wetland, iron concentrations ranged from 0.06 to 0.37 mg/l with twoexceedances on 8/13/03 and 8/28/03. The median concentration was 0.11 mg/l.Manganese was present in 22 of the 24 samples with concentrations ranging from 0.01 to0.03 mg/l. None of the samples exceeded SDWS. The median concentration was 0.02mg/l.

In the basin, iron concentrations ranged from 0.04 to 6.00 mg/l, with eightsamples exceeding the SDWS. The median value was 0.0.23 mg/l. Manganese wasdetected in 19 of the 24 samples with concentrations ranging from 0.012 to 0.060 mg/lwith only one sample above SDWS. The median concentration was 0.03 mg/l.

When the cooling pond was used as a source of water, the import of iron andmanganese were quite low with median values of 0.04 and 0.01 mg/l, respectively. The

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median concentrations of iron and manganese increased by 3.5 and 3.0 times while thewater flowed through the wetland. The median concentration of the iron increased morethan 8 times while percolating through the filter basin leading to the supposition that ironwas leached from the tailing sand or was present in groundwater seeping from outside ofthe filter basin into the filter basin. Field observations of IRB biofilm formation in the SS

support this supposition. As a further proof, the data collected from the NS and the SSclearly indicated that the iron concentration varied considerably with the water from theNS being significantly lower. This led to the conclusion that the SS acted as aninterceptor drain to catch influent seepage, while the NS received percolating wetlandwater from the surface recharge system. This is further supported by the fact that themedian iron concentrations in the basin water when the effluent was used were 0.23 mg/l,which is below the SDWS. This happened because the change in sample location to theNS occurred at approximately the same time as the switch to using effluent as a source.Based on this information, it is realistic that the large iron concentrations in the basinwater could be primarily due to high iron concentrations in the groundwater seeping intothe filter basin and intercepted by the south filter pipe. This hypothesis is further

supported by the fact that the median manganese concentrations in the basin waterdeclined from 0.07 to 0.03 mg/l, a 57% reduction after the source and sampling pointswitch. No actual samples of the groundwater outside the filter basin were collected andanalyzed.

Fluoride

It is interesting to note that there are different standards for the same chemicalcompound in the drinking water standards. In the PDWS, the standard for fluoride is4.00 mg/l, while in the SDWS it is 2.00 mg/l. The lower SDWS level is an advisory levelfor families with children below the age of 9 years. Fluoride concentrations between 2.00and 4.00 may affect the development of teeth in children. Fluoride was present in all thesamples from the cooling pond, wetland, and filter basin. In the cooling pond, fluorideconcentrations exceeded the SDWS in all samples with the concentrations ranging from2.30 to 2.80 mg/l, and a median value of 2.50 mg/l. The fluoride concentrations in thewetland when the cooling pond was used as a source were above the SDWS for 11 of 25samples and ranged from 1.10 to 2.70 mg/l, with a median value of 2.00 mg/l. In thebasin, fluoride concentrations exceeded the SDWS in 13 of the 26 samples and rangedfrom 1.40 to 2.50 mg/l, with a median value of 1.95 mg/l.

Fluoride was present in the effluent discharge, wetland, and basin in all samples.In the effluent discharge, fluoride concentrations ranged from 0.11 to 0.38 mg/l, with amedian value of 0.27 mg/l. The fluoride concentrations in the wetland using the effluentas a source ranged from 0.7 to 2.2 mg/l, with a median value of 0.93 mg/l, and exceededSDWS in three samples out of 23. In the basin, fluoride concentrations exceeded theSDWS in 8 out of the 23 samples, ranging from 1.1 to 3.3 mg/l. The medianconcentration was 1.70 mg/l.

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It is interesting to note that when the cooling pond was used as a source, themedian fluoride values in the samples from the filter basin declined by 22% incomparison to the cooling pond water. When the effluent was used as a source themedian concentrations in the samples from the filter basin increased more than six timesin comparison to the effluent. In both cases, the median values still met the SDWS and at

no time did any sample (from any location) ever exceed PDWS.

Sodium, Chloride and Sulfate

The PDWS for sodium is 160 mg/l, and SDWS is 250 mg/l for chloride andsulfate. In this section, the sodium and chloride concentrations are used as conservativemarkers and their fate in the treatment system is compared to that of sulfate. Sodiumconcentrations ranged from 76 to 85 mg/l (with a median of 77.5 mg/l) in the coolingpond, 34 to 80 mg/l (median 69.5 mg/l) in the wetland, and 35 to 79 mg/l (median 61.0mg/l) in the basin.

When the effluent was used as a source, the sodium concentration ranged from 37to 85 mg/l (median 58.5 mg/l) in the effluent, 31 to 86 mg/l (median 43.0 mg/l) in thewetland, and 32 to 75 mg/l (median 44.0 mg/l) in the basin.